Colorless petroleum marker dyes

ABSTRACT

A composition comprising a liquid petroleum product and a colorless marker compound in an amount that is not detectable visually, and a method for marking a liquid petroleum product with a colorless marker compound.

BACKGROUND

[0001] This invention relates generally to a composition comprising acolorless marker dye and a liquid petroleum product, and to a method formarking petroleum products.

[0002] Certain phthalein derivatives are known and used as markers inpetroleum applications and other industrial applications such as paintsand plastics. For example, U.S. Pat. No. 6,002,056 describes the use ofthymolphthalein, cresolphthalein and related compounds as markers forpetroleum products. However, this reference discloses only compoundshaving two phenolic hydroxyl groups, and does not suggest the use ofphthalein esters as markers.

[0003] The disadvantages of phthalein derivatives stem from theirtypically low solubility in petroleum products. As a result of thischaracteristic, phthalein markers can be removed from a marked petroleumproduct by extraction with water, either deliberately by one seeking tocircumvent the marking, or as a result of contact of the markedpetroleum product with water bottoms in storage tanks.

[0004] The problem addressed by this invention is to find colorlessmarker dyes with improved solubility in petroleum products.

STATEMENT OF INVENTION

[0005] The present invention is directed to a composition comprising aliquid petroleum product and a compound of formula I in an amount thatis not detectable visually.

[0006] In formula I, R¹ is C₁-C₁₈ alkyl, C₁-C₁₈ alkenyl, aryl oraralkyl; R², R³ and R⁴ are independently hydrogen, C₁-C₁₂ alkyl, chloroor bromo; and R⁵ is hydrogen, chloro or bromo.

[0007] The present invention is further directed to a method of markinga liquid petroluem product comprising adding to the petroleum product asa marker an amount of a compound of formula I that is not detectablevisually, and wherein the marker develops a color on contact with adeveloping reagent.

DETAILED DESCRIPTION

[0008] An “alkyl” group is a hydrocarbyl group having from one toeighteen carbon atoms in a linear, branched or cyclic arrangement.Substitution on alkyl groups of one or more halo, alkoxy, alkanoyl oramido groups is permitted; alkoxy, alkanoyl and amido groups may in turnbe substituted by one or more halo substituents. Preferably, alkylgroups are unsubstituted. An “alkenyl” group is an “alkyl” group inwhich at least one single bond has been replaced with a double bond. An“aryl” group is a substituent derived from an aromatic compound,including heterocyclic aromatic compounds having heteroatoms chosen fromamong nitrogen, oxygen and sulfur. An aryl group has a total of fromfive to twenty ring atoms, and has one or more rings which are separateor fused. Substitution on aryl groups of one or more halo, alkyl,alkenyl, alkoxy, alkanoyl or amido groups is permitted, withsubstitution by one or more halo groups being possible on alkyl,alkenyl, alkoxy, alkanoyl or amido groups. Preferably, aryl groups areunsubstituted or are substituted only by halo or alkyl groups. An“aralkyl” group is an “alkyl” group substituted by an “aryl” group.

[0009] It is preferred that R², R³ and R⁴ are hydrogen or alkyl havingfrom one to four carbon atoms. It is also preferred that R¹ is alkylhaving from one to four carbon atoms. It is preferred that R⁵ ishydrogen.

[0010] It is preferred that the liquid petroleum product is gasoline,diesel fuel, jet fuel, fuel oil, kerosene or lamp oil. It is preferredthat the compound of formula I is present in an amount from 0.5 ppm to100 ppm, and further preferred that it is present in an amount from 0.5ppm to 10 ppm. It is preferred that the compound of formula I isprepared as a mixture with a high-boiling hydrocarbon-soluble solvent.Preferred solvents include 1-octyl-2-pyrrolidone, mixedmethylnaphthalenes (sold as AROMATIC 200 by Exxon Corporation) oraromatic hydrocarbon solvents. The preferred concentration of the markerin the solvent is from 20% to 30%.

[0011] The developing reagent is a strongly basic reagent, e.g., ahydroxide of an alkali metal or of a quaternary ammonium ion.Preferably, the reagent is a quaternary ammonium hydroxide.

[0012] This invention is further directed to the compound of formula Iin which R¹ is propyl, R² is methyl, and R³, R⁴, and R⁵ are hydrogen.Preparation of this compound is described in Example 1.

EXAMPLES Example 1 Preparation of the Di-n-Butyl Ester ofo-Cresolphthalein

[0013] To a 100 mL, three-neck round-bottom flask fitted with a stirrer,thermocouple and a condenser, the following raw materials were added:(1) o-cresolphthalein, 1.73 g (0.005 moles); (2) water, 30 mL; (3) 50%NaOH, 0.8 g; (4) Na₂CO₃, 0.6 g; and (5) xylenes, 8 g. The mixture wasstirred at 20-25° C. for one hour, during which butyric anhydride, 2 g,was added. The mixture was then heated to 50-55° C. until TLC revealedthat the esterification reaction was complete. The upper xylenes layerwas separated and 1-octyl-2-pyrrolidone, 2.5 g was added to it. Xylenesand water were removed azeotropically under vacuum. A residue of 6.6 gwas obtained.

[0014] A marker solution was prepared by dissolving a 100 mg portion ofthe residue in xylenes (100 mL), and diluting 1 mL of the resultingsolution to 100 mL with kerosene to make a 10 ppm solution.

[0015] A developer was made by dissolving 1 g of a 40% solution ofbenzyltrimethylammonium hydroxide in methanol in 99 g of2-ethyl-1-hexanol. To a 10 mL portion of the 10 ppm marker solutionprepared above was added 2.5 mL of the developer. After the mixture wasshaken for a few seconds, it acquired a blue-purple color. If necessary,quantitative determination of the marker concentration can beaccomplished by measuring the absorbance of the solution at a wavelengthof 581 nm.

[0016] A 10 mL portion of the 10 ppm solution prepared above was stirredwith 10 mL of water for ½ hour and the layers were separated. To theorganic layer was added 2 mL of the developer solution, resulting indevelopment of a blue-purple color. Addition of 2 mL of developersolution to the water layer gave no color. This indicated that themarker was not extracted into the water layer.

1. A composition comprising a liquid petroleum product and a compound having the formula

wherein R¹ is C₁-C₁₈ alkyl, C₁-C₁₈ alkenyl, aryl or aralkyl; R², R³ and R⁴ are independently hydrogen, C₁-C₁₂ alkyl, chloro or bromo; and R⁵ is hydrogen, chloro or bromo; and wherein said compound is present in an amount that is not detectable visually.
 2. The composition of claim 1 in which said compound is present in an amount from 0.5 ppm to 100 ppm.
 3. The composition of claim 2 in which said liquid petroleum product is gasoline, diesel fuel, jet fuel, fuel oil, kerosene or lamp oil.
 4. The composition of claim 3 in which R², R³ and R⁴ are hydrogen or alkyl having from one to four carbon atoms.
 5. The composition of claim 4 which R¹ is alkyl having from one to four carbon atoms and R⁵ is hydrogen.
 6. A compound having the formula


7. A method of marking a liquid petroluem product comprising adding to the petroleum product as a marker a compound of formula

wherein R¹ is C₁-C₁₈ alkyl, C₁-C₁₈ alkenyl, aryl or aralkyl; R², R³ and R⁴ are independently hydrogen, C₁-C₁₂ alkyl, chloro or bromo; and R⁵ is hydrogen, chloro or bromo; wherein the compound is not detectable visually, and wherein the compound develops a color on contact with a developing reagent.
 8. The method of claim 7 in which said compound is present in an amount from 0.05 ppm to 100 ppm.
 9. The method of claim 8 in which said liquid petroleum product is gasoline, diesel fuel, jet fuel, fuel oil, kerosene or lamp oil.
 10. The method of claim 9 in which R², R³ and R⁴ are hydrogen or alkyl having from one to four carbon atoms, R¹ is alkyl having from one to four carbon atoms and R⁵ is hydrogen. 